Process of preparing methyl betafurfuryloxypropionate



Patented Apr. 18, 1950 UNITED STATES- PATENT OFFICE PROCESS OF PREPARINGMETHYL BETA- FURFUREZLQXYPROlIQNATE Chessie E. Rehberg, Glenside, andCharles H. Fisher, Abington, Pa, assignors 'to the United States of"America as represented by the Secretary of. Agriculture No Drawing;Application February 12, 194.8, SeriaLNo. 8,016

1 Claim.

zoo-345) (Granted under the act of March. 3,. 1883, as amended April 30,1928; 370 0. G. 757.)

ROCHzCHzCOOR' wherein R and R. are alkyl radicals, such as methyl,ethyl, and so forth, or substituted alkyl radicals such as chloropropyl,alkenyl radicals such as allyl, and aralkyl radicals such as benzyl, andto methods for the preparation of such esters.

The object of the invention is to produce: new

compounds which are useful as solvents, plasti-- cizers, chemicalintermediates, and so forth. Other objects and advantages will beapparent frdm' the description of the invention.

It is to be understood that, wherever the term alkyl is used herein, itincludes substituted alky and. that, wherever the term alkoxypropionateis used, it includes substituted alkyl.

oxypropionate.

We have discovered that primary and. secondary alcohols, under suitableconditions, will react with various acrylic esters in accordance withthe following Equation I:

Equation I This reaction comprises two distinct. steps: (1) addition ofalcohol to the oleflnic double bond of the acrylic ester, and (2)alcoholysis of the ester resulting from this previous step. Wehavediscovered further that these steps can. be carried out eitherconcurrently or separately. Thus, we can produce the product shown inEquation- I either in a single operation, as shown in. Equa tion I, orin two separate operations, as shown in the following Equation II andIII:

Equation 11 CH2: CHCOOR+ROH R OCHzCHzCOOR Equation III The reactionrepresented by Equation I has. the advantage of being a one-stepprocess, while on.

the other hand. the two-step processrepresented by Equations II and IIIhas the advantage of producing a product ROCHzCI-IzCOOR", wherein R andR." may be either the same or different, thus making it possible toprepare a much greater variety of products than can be obtained by the.one-step process.

The oxy-esters of the invention can. also be prepared using the theoryof the aboveequations. by reacting an acrylic ester with an ethyleneglycol or polyethylene glycol mono-ether, and the resulting product thentreated with an ethylene gly-a col or polyethylene glycol. monoalkylether to yield a higher oXy-ester.

High yields are obtained in the reactions represented by Equations I andII only when pri-' mary or secondary alcohols of relatively lowmolecular weight are used. The molecular Weight of the alcohol, however,is relatively unimportant in the step represented by Equation III.

For the reactions shown in Equations I and II, a strong alkalinecatalyst such as an alkali metal alcoholate is suitable, whilefor thereaction shown in Equation III an esterification catalyst of either theacidic type, such as sulfuric or arylsulfonic acid, or the alkalinetype, such as an alkali metal alcoholate, may be used. However, theacidic type in general is preferred.

In general, the reaction in accordance with Equation I utilizes thefollowing procedure:

A low molecular weight acrylic ester, such as methyl acrylate,preferably containing about 2 to 5 percent by weight of an alkalinepolymerization inhibitor, such as phenyl-beta-naphthylamine ordiphenylamine, is stirred and kept at or below room temperature whilethere is added slowly 2 to 4 molecular equivalents of an alcohol ofboiling point than that of the alcohol which will be formed by thereaction, said alcohol being added having dissolved in it about 0.5 to5.0

parts by weight of sodium for each. 100 parts of acrylic ester used,When all of the alcohol has been added, the mixture is slowly warmed andfinally refluxed under a fractionating column which is so arranged. thatthe low-boiling alcohol.

which is liberated in the reaction can be continuously or intermittentlydistilled from the reaction mixture. Frequently, this" low-boiling.a'lcohol will distill as an azeotrope with the acrylic? ester used asthe reagent. If desired, another material such as a hydrocarbon liquidof. suitable.

boiling point maybe added to thereactionv ture to remove thelower-boiling. alcohol as a. hy

drocarbon-alcohol azeotrope. When no more of the alcohol is produced themixture is cooled, acidified with acetic acid, and distilled.Distillation under reduced pressure is generally preferred so that thecrude material is not heated above 100 to 150 C. in the still pot.

The reactions in accordance with Equation III utilize the followingprocedure:

The oxy-ester is treated with three molecular equivalents of alcohol,using as a catalyst about 2 g. of sulfuric or toluenesulfonic acid. Thmixture is then refluxed in a flask fitted with a 3-foot i'ractionatingcolumn, the column having a stillhead suitable for operation eitherunder total reflux or with partial take-01f. The still is operated undertotal reflux until the temperature at the still-head drops to theboiling point of the lower-boiling alcohol being produced in thereaction or to the boiling point of the azeotrope containing thisalcohol if such an azeotrope is present. The distillate is then slowlycollected as long as the lower alcohol continues to be produced. When nomore such alcohol is produced, the reaction mixture is fractionallydistilled at a pressure such that the still pot is not heated aboveabout 150 C.

The following are examples of the invention, and data including somephysical properties of the resulting products are shown in theaccompanying table, which in addition lists various other new compoundsproduced by the above procedures.

Examples 1 and 2 are illustrative of reactions in accordance withEquation I.

Example 1 Preparation of n-batyl beta-n-batoxypropz'onate.-Two moles(1'72 g.) of methyl acrylate in which are dissolved about 5 g. ofphenyl-betanaphthylamine as an alkaline polymerization inhibitor arestirred and kept below 40 C. while 8.0 moles (592 g.) of n-butanolhaving 3.0 g. of sodium dissolved in it are slowly added. The mixture isslowly heated to boiling in a flask attached to a 3-foot fractionatingcolumn. The column is operated under total reflux until the temperatureat the still-head drops to about 62 to 63 C., the boiling point of themethyl acrylatemethanol azeotrope. This azeotrope is then distilled asrapidly as formed until no more methanol is liberated. The reactionmixture is then cooled, acidified with acetic acid, and distilled. Theexcess alcohol is distilled at about 56 C. and at about 50 mm. pressure.A small amount of methyl beta-butoxypropionate is distilled at about 75C. and at about 6 mm. pressure, after which the main product, n-butylbeta-n-butoxy-" propionate, is distilled at about 106 C. and at about 5mm. pressure.

Example 2 Example 3 Preparation of methyl beta-methoxypropionate.-Methylacrylate is stirred and kept below 35 C. while one molecular equivalentof methanol.

containing 1 g. of sodium for each g. of

methyl acrylate is slowly added. The mixture is allowed to standovernight at room tempera- Example 4 Preparation of methyl betaethoxypropiomate-Using substantially the same procedure as in Example 3above, methyl acrylate is treated with ethanol to produce methylbeta-ethoxypropionate.

Example 5 Preparation of methyl beta-n-butoxypropiomatte-By proceedingsubstantially as in Example 3 above, methyl acrylate is treated withnbutanol to produce methyl beta-n-butoxypropionate. The yield issubstantially unchanged by either allowing the reaction mixture to standat room temperature for only about 3 to 4 hours before distilling, orrefluxing the mixture for 8- hours after it has stood overnight at roomtemperature and then distilling.

Example 6 Preparation of methyl beta-sec-butoxypropionate-One mole ofsec.-butanol, three moles of methyl acrylate, 1 g. of sodium and about 5g.

of phenyl-beta-naphthylamine are mixed as in Example 3 above, and thenrefluxed for about 1 hour. After acidification with acetic acid themixture is distilled.

Example 7 Preparation of ethyl beta-ethoxyprop onate.' By proceedingsubstantially as in Example 3 above, ethyl acrylate is treated withethanol:

containing sodium ethoxide. The mixture is allowed to stand overnightbefore being distilled.

Example 8 Preparation of isobutyl beta-methoxypropionate.-By proceedingsubstantially as in Example 3 above, isobutyl a'crylate is treated withmethanol and sodium methoxide. The mixture is kept below 40 C. andallowed to stand overnight before being acidified and distilled.

Examples 9 to 11, inclusive, are illustrative of reactions in accordancewith Equation III.

Example 9 Preparation of Z-ethyltutyl beta-methoxypropionate-One mole ofmethyl beta-methoxypropionate is treated with three moles of2-ethylbutanol and 1.5 cc. of sulfuric acid. After refluxing for about12 hours with slow distillation of methanol, the mixture is fractionallydistilled.

Example 10 Preparation of scc.-batyl beta-methoxypropi-- onate.-Usingsubstantially the same procedure as in Example 9 above, methylbeta-methoxypropionate is treated with sec.-butanol, using tolu--'enesulfonic acid as a catalyst.

v Example 11 Preparation of beta-ethoxyethylbeta-methoxypropionate.-Methyl beta-methoxypropionate is treated withbeta-ethoxyethanol, the catalyst being toluenesulfonic acid.

The following table lists some oXy-esters produced by our invention andsome of their physical properties. R and R, which may be alkyl orsubstituted alkyl, alkenyl, and aralkyl radicals, are those radicalsapplicable to the general formula 6 one of the following esters aredissolved in acetone, it is found that all of the mixtures arecompatible, and when the solvent is allowed to ROCHzCHzCOOR' evaporateand the resulting films are cured for Properties Boiling Point PerExample R R Refnw Cent tive Index Yield Temp. Pressure N4 4 in G. in mm.

75. 5 17 l. 4260 0. 9884 82 119 3 1. 4993 35 l hyl 113-118 20 1. 4227 0.9247 38 beta-chlorc-ethyl. beta-chloro-ethyL 99-100 1 1. 4633 1. 2865 27gamma-chlorogamma-chloro- 130-136 1 1.4589 1.1640 39 propyl. propyl.

Example 23 Preparation of methyl beta-furfurylomypropionate.--Methylaorylate is stirred and kept below 35 C. while there is slowly added onemolecular equivalent of furfuryl alcohol in which has been dissolvedabout 1 g. of sodium per 100 g. of alcohol. After the addition iscomplete, the mixture is allowed to stand at room temperature for aboutfrom 12 to 24 hours. It is then acidified with acetic acid and distilledin vacuum. After removal of unreacted materials the product, methylbeta-furfuryloxypropionate, is distilled at 127 C. (12 mm. pressure). Ayield was obtained. The product is a colorless, mobile liquid,

Nd =1.4693 and D4 =1.1278

Furfuryl alcohol may also be added to other acrylic esters, such asethyl, butyl, octyl, betaethoxyethyl, beta-butoxyethyl,tetrahydrofurfuryl, allyl, benzyl, and beta-chloroethyl acrylates,

to produce the corresponding oxy-esters.

From these examples and the foregoing discussion, it is evident that avery wide variety of oxy-esters can be made in accordance with ourinvention. In general, the reactions represented by Equations I and IIgive high yields of the desired products only when the alcohol used asthe other reagent is one of relatively low molecular weight. For thisreason, we prefer to prepare oxy-esters of the higher alcohols byalcoholysis of the ester of a lower alcohol in accordance with EquationIII.

The esters prepared in accordance with this invention are clear,colorless liquids of relatively low vapor pressure and are useful assolvents, plasticizers, chemical intermediates, or resin intermediates.These esters are compatible with cellulosic derivatives such as ethylcellulose and are useful as plasticizers for such derivatives. Thus,when equal weights of ethyl cellulose and 24 hours at C., the filmsfinally obtained exhibit the following characteristics:

Plastioizer Plastic isoamyl befa-methoxypropionate ethoxyethylbeta-methoxypropionate. gamma chloropropyl beta-methoxypropion ve. ethylbeta-ethoxypropionate n-butyl beta-u-butoxypropionate methylbota-furfuryloxypropionate clear, tough, flexible.

Do. clear, brittle.

Do. clear, tough, flexible. brown, brittle.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,196,747 Dickey et a1 Apr. 9,1940 2,196,750 Dickey et a1 Apr. 9, 1940 2,433,866 Rehberg et a1 Jan. 6,1948 OTHER REFERENCES Koelsch, Jr. of Am. Chem. Soc., vol. 65, page 438.

